The primary aim of this proposal is to document the nature and course of abrupt neuroleptic withdrawal induced effects on sleep EEG. Although sleep disturbance during the first two weeks of chronic treatment discontinuation is frequently observed clinically, there are very few systematic studies evaluating this phenomenon. Such sleep disturbance and associated irritability may mimic prodromal symptoms of psychosis relapse and influence clinical judgement regarding resumption of drug treatment. To study any withdrawal effect on sleep, we propose instituting neuroleptic treatment baseline sleep EEG recordings, followed by a double blind, placebo substituted, abrupt drug discontinuation and sleep EEG for seven consecutive withdrawal nights. Patients will be kept drug-free for at least four weeks at the end of which baseline drug-free sleep studies will be conducted. During the entire protocol, frequent blood drawings, for hormonal assay, and weekly Brief Psychiatric Rating Scale evaluations will be carried out. Our preliminary data of five schizophrenic in patients shows a maximum average 50% decrease in REM sleep and an increase in REM latency following neuroleptic withdrawal. Although, exact mechanism of this withdrawal phenomenon is not clear, we postulate that it may reflect chronic neuroleptic treatment induced adaptational changes in catecholaminergic system. Therefore, to explore this hypothesis, we propose to further study the effect of drug withdrawal on plasma prolactin another putative DA-mediated parameter. Antipsychotic drugs, presumably through their interaction with DA receptors, have a prolactin stimulating effect on acute administration; however, a varying amount of tolerance develops to this effect following chronic treatment. We postulate a rebound prolactin lowering effect below the drug-free baseline level after neuroleptic withdrawal. Statistical analysis will be carried out to ascertain quantitative and chronological relationships between the changes in sleep and neuroendocrinologic parameters following drug withdrawal. Furthermore, relationship between withdrawal induced maximum changes in sleep and neuroendocrinologic parameters from drug-treatment and drug-free baseline values will be correlated with any increase in psychotic symptoms during the drug-free period. This provides us with a preliminary opportunity to explore whether "rebound" changes in sleep EEG and plasma prolactin following drug withdrawal can predict subsequent relapse.